I presume you mean you have attached a pen-drive to one of your Mac's USB ports. The computer should automatically recognise it and display a drive icon on the right-hand side of the desktop just like floppy discs used to do. Double-click it to open it up. When finished with it, drag the icon to the Trash and you'll be prompted to remove the pen-drive from the port.
If you are not seeing the drive icon, then maybe your desktop has become very cluttered? If so, clear a space on the RHS and try re-attaching the drive.
If you have dragged the icon to the Trash, but not removed the drive, you won't see its icon, or be able to access it, until you remove the drive and re-insert it.
WRT your last Qu. No, this site does not support photos, but you can post links to its location elsewhere on the internet.